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Metal-insulator-metal (MIM) capacitors with crystalline-TiO2/SiO2 stacked dielectric are explored in this letter. The crystalline TiO2 possesses a high permittivity while the SiO2 provides a negative quadratic voltage coefficient of capacitance (VCC-α) to cancel out the positive VCC-α from the crystalline TiO2. These desirable properties render MIM capacitors with high performance in terms of a capacitance density of 11.9 fF/μm2 with a VCC-α of 90 ppm/V2. With additional N2 plasma treatment on the crystalline TiO2, because of the effective passivation of grain-boundary-related defects and, consequently, a lower leakage current by a factor of 50, the VCC-α can be further lowered to 30 ppm/V2 with slight degradation in capacitance density to 11.2 fF/μm2, which well meets the requirement in 2018 set by ITRS.
Date of Publication: Jan. 2012